AT&T UNIX™PC Unix System V Users Manual - tenox

CTIME (3C) CTIME(3C)
The external long variable timezone contains the difference, in
seconds, between GMT and local standard time (in EST, timezone
is 5*60*60); the external variable daylight is non-zero if and only
if the standard U.S.A. Daylight Savings Time conversion should
be applied. The program knows about the peculiarities of this
conversion in 1974 and 1975; if necessary, a table for these years � 1
can be extended.
I
If an environment variable named TZ is present, asctime uses the
contents of the variable to override the default time zone. The
value of TZ must be a three-letter time zone name, followed by a
number representing the difference between local time and
Greenwich Mean Time in hours, followed by an optional threeletter
name for a daylight time zone. For example, the setting for
New Jersey would be ESTiiEDT. The effects of setting TZ are
thus to change the values of the external variables timezone and
daylight; in addition, the time zone names contained in the external
variable
char •tzname[2] = { "EST", "EDT" };
are set from the environment variable TZ. The function tzset sets
these external variables from TZ; tzset is called by asctime and
may also be called explicitly by the user.
Note that in most installations, TZ is set by default when the user
logs on, to a value in the local /etc/ profile file (see profile(4)).
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time(2), getenv(3C), profile( 4), environ(5). 1
BUGS
The return values point to static data whose content is overwritten
by each call.
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